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September 13, 2012

Accelerated Glacial Melt in Parts of Himalayas Could Be a Mixed Bag for Inhabitants of the Region

by Alan McStravick for redOrbit.com - Your Universe Online

Alan McStravick for redOrbit.com - Your Universe Online

A report, issued this week by the National Research Council (NRC) has concluded that glacial melt in the Eastern and Central Himalayas has accelerated at an alarming rate, while glaciers in the Western Himalayas may actually be growing. Researchers say that this trend could have both positive and negative consequences for local inhabitants and ecosystems.

These massive glacier-capped mountains, often referred to as the water towers of Asia, are the headwaters for several major river systems, including the Yellow, Yangtze, Mekong and Ganges rivers, among others. All told, nearly one quarter of the Earth´s population relies on these glaciers for drinking water and irrigation.

But the study´s authors caution against exaggerated alarm. While melting glaciers do play a role in replenishing the region's rivers and streams, the lower-elevation regions still depend mostly on on monsoon rains and snow melt.

The committee noted that melting glaciers can actually play a positive role in renewing water sources during times of drought. Referring to the European drought of 2003, they noted that glacial runoff into Europe´s Danube river was at a 100-year high. Viewed in this light, the melting of the Himalayas glaciers may serve as a sort of ecological buffer that will add water to blighted rivers and streams at the times when they are most needed.

While the effects are clearly visible, the exact causes of the accelerated glacial melt remain elusive. The committee seems to be in agreement with other studies that have identified desert dust and black carbon as culprits in the warming of the region. Black carbon refers to the fine soot and ash produced by diesel exhausts, thermal power plants, brick kiln smokestacks and forest fires. The evidence seems to indicate that the increase in black carbon deposits on the Himalayan glaciers are causing them to absorb more sunlight, acting as an accelerant in glacial and snow melt.

As India and China have risen to prominence amongst the industrialized nations of the globe, their overall output of pollutants, including black carbon, has had a measurable effect on the environment of the region.

“Although glacier melting is predominantly due to global temperature rise, the deposition of pollutant particles like black carbon can enhance this effect,” said Paolo Bonasoni of the Italy-based Institute of Atmospheric Sciences and Climate (ISAC).

The consequences of this rapid glacial melt are far-reaching and could potentially be devastating to a large portion of the global population. Noted in a study by Tandong Yao, Director of the Institute of Tibetan Research at the Chinese Academy of Sciences, and Lonnie Thompson, glaciologist and paleoclimatologist at Ohio State University, the melting snow and glacial run-off from the Himalayas could produce what are known as glacier-lake outbursts, leading to flooding that could threaten the lives and livelihoods of the populations that rely upon these river systems.

"The majority of the glaciers have been shrinking rapidly across the studied area in the past 30 years," according to Yao's study published in the journal Nature Climate Change.

A prolonged glacier retreat would both increase the volume of water in the rivers as well as the levels of sediment that they carry, which could choke water supply and disrupt agriculture, the study says.

In this study, the Gravity Recovery and Climate Experiment (GRACE) satellite mission was used to create models to extrapolate data about the melt and its potential effects. Thompson says it is also important to look at the longer-term picture because climate is generally considered a 30-year average of weather trends.

As an example, the Naimona´nyi Glacier that feeds the Indus River shrank by 508 feet during a 30-year sample period, or about 16.4 feet annually.

"We were surprised to find that at 19,849 feet [where the glacier is located] there had been no net accumulation [of ice] since the late 1940s," Thompson told IRIN, the news service of the U.N. Office for the Coordination of Humanitarian Affairs.

Many experts speak of an impending tipping point in global warming, a time when humans will no longer be able to repair or even affect the trajectory of the earth´s climate. These reports indicate that something drastic is occurring. The effects are increasingly visible and the cost of seeming inaction and political paralysis may be the legacy we never get to leave behind.